body {
  background-color: #303952;
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100vw;
  height: 100vh;
}
#app {
  width: 400px;
  /* flex-wrap: wrap; */
  display: flex;
  border: solid 10px rgba($color: #fff, $alpha: 0.2);
  div {
    width: 200px;
    height: 200px;
    &:nth-of-type(1) {
      background-color: #f6e58d;
      flex-shrink: 0;
    }
    &:nth-of-type(2) {
      background-color: #ff7979;
      flex-shrink: 1;
    }
    //200-200/(200*1+200*3)*3*200
    &:nth-of-type(3) {
      background-color: #7ed6df;
      flex-shrink: 3;
    }
  }
}
